Re: Chokes vs Safety Gaps

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Jim Lux <jimlux-at-earthlink-dot-net> 

At 07:56 AM 2/9/2004 -0700, you wrote:
>Original poster: Mark Broker <mbroker-at-thegeekgroup-dot-org>
>I fail to see how a ~1mH choke in series with a ~1kH iron-cored 
>transformer secondary will provide any protection whatsoever.  If used in 
>conjunction with an RC circuit, then that could be bad, too.


Speculating here... A difference would be that an RF choke outside the 
transformer might be able to take a fairly HV, fast edged transient without 
failure.  The poorly insulated windings designed for minimum manufacturing 
cost inside a NST probably can't.  If the external choke slows down the 
rise time, then the huge leakage C inside the NST windings won't be as big 
a deal, so the voltage in the transient has a chance to be more evenly 
distributed within the winding.



>http://hot-streamer-dot-com/TeslaCoils/MyPapers/rlcfilter/rlcfilter.html
>
>A properly-set safety gap will just barely not fire at full operating 
>voltage without the primary capacitor connected, so I fail to see how a 
>properly-set safety gap with a properly-tuned and operated TC will be 
>ineffective or affect performance....  IME a safety gap will not fire 
>unless the TC is out of tune or the power supply is overvolted via an 
>overvolting variac.


A gap misfire/mistiming could result in a transient voltage that's somewhat 
higher than normal, and the safety gap would fire.  Also, things can happen 
like "alligator clip falls off primary" or "ground on secondary comes 
undone" or "capacitor fails and coil goes grossly out of tune".  That's why 
it's called a "safety gap".



>My 2 cents.
>
>Mark Broker
>Chief Engineer, The Geek Group
>
>
>On Sun, 08 Feb 2004 21:24:41 -0700, Tesla list <tesla-at-pupman-dot-com> wrote:
>
>>Original poster: "Gary  Weaver" <gary350-at-earthlink-dot-net>
>>If you adjust the safety gap so it won't fire then it doesn't do anything so
>>why have it.  If you adjust the safety gap so it fires then it takes power
>>away from your coil and the discharge sparks get shorter don't want that
>>either.  A choke coil provides all the protection needed to protect the
>>transformer from feedback so the safety gaps are a waste of time.
>>
>>Gary Weaver
>